The file of this patent contains at least one color drawing. Copies of the patent with color drawings will be provided by the PTO upon payment of necessary fee.
1. Field of Invention
This invention relates to devices used to align equipment with distant objects or targets.
2. Prior Art
Because of simplicity of design and traditional acceptance, peep sights have been used on all types of equipment that requires alignment with distant objects or targets.
A current peep sight is a rear-mounted device consisting of a thin plate made of rigid material with a round aperture near the center. FIG. 2 shows a peep sight 26 and a front sight 28 mounted on top of a piece of equipment 27. The front sight is a free standing pin. A person sighting the equipment, aligns the aperture of the peep sight with the front sight, and a target, 30. The person""s ability to sight on the target accurately, is directly dependent on the alignment of the peep sight""s aperture, the front sight, and the target. The distance between the target and the front sight is many times greater than the distance between the peep sight and the front sight. A small inaccuracy in the alignment of the two sights will cause a great inaccuracy in the alignment of the equipment with the target.
Current peep sights are a round apertured peep sight or its variations. Two variations of the round apertured peep are a cross hair peep, and an adjustable peep. The current peep sight fail to address the inadequacies caused by light diffracted within its aperture.
Diffraction of light describes a phenomenon. The phenomemon results in the bending of light toward an obstacle, as the light passes near the obstacle. Why diffraction occurs has not been totally proven, but its effects has been known for centuries. The figures below taken from xe2x80x9cPhysicsxe2x80x94Principles with Applicationsxe2x80x9d, Douglas C. Giancoli, author, illustrates the effects of Huygens"" principle is consistent with diffraction (FIG. 14A) around the edge of an obstacle, (FIG. 14B) through a large hole and (FIG. 14C) through a small hole whose size is on the order of the wavlength of the wave.
FIG. 14A illustrates how light traveling left to right is diffracted by an obstacle. Diffraction alters the lights direction. Light passing near an obstacle bends toward the obstacle. Diffraction also reduces the intensity of the light by spreading it over a greater area. Because light is bent toward the edge, a person viewing the edge of the obstacle would not actually see the edge. The person would only see an image of the edge created by diffracted light. The viewer is seeing a false edge of the obstacle.
FIG. 14C illustrate the effect of light diffraction as light passes through a small aperture or hole. The aperture being small and the diffraction occuring perpendicular to its edges causes the aperture to appear closed.
FIG. 14B illustrates the effects of light diffraction as light passes through a large aperture or hole. Light passing near the edge of the aperture diffracts outward. Light reflecting off the edges of the aperture bends outward. A viewer never sees the aperture, only an image where diffracted and undiffracted light separate. The viewer sees a false aperture. The size and shape of the aperture the viewer sees is dependent on the light diffracted inside the aperture. When light intensity is inconsistent, the effect of light diffraction is inconsistent. Light passing through the aperture may be more intense to the right. The effect of the light diffraction would be less detectable to the right. The center of the aperture would appear more to the right. Since the viewer never sees the true aperture, the viewer will misalign the aperture and the equipment.
Light diffraction also reduces the intensity of the light passing through a currently designed peep aperture. When light is dim, a person may be able to see a target with out a peep, but be unable to see the target through the peep.
Oversizing a peep aperture is a current approach to avoiding the effects of diffracted light. FIG. 14B illustrates light passing through a large aperture. By oversizing the aperture, light near the center of the aperture will not be diffracted. Increasing the size of the aperture also increases the inaccuracy of the peep. A large aperture is more difficult to align with a front sight and a target then a small aperture. Also oversizing the peep aperture dose nothing to eliminate the affects of a false aperture.
A cross hair peep can eliminate the inaccuracy created by a false aperture. In doing so the cross hair peep creates additional light diffractions. The cross hair peep consists of a large peep aperture with two thin bars (hairs), one vertical and one horizontal. These bars intersect at the center of the aperture. The thin bars (hairs) provide the user with a consistent location for the center of the peep aperture. A user now aligns the intersection of the cross hairs with the front sight and the target. Compared to a other peeps, the cost of manufacturing the cross hair peep is many times greater. Making and installing the intersecting cross hairs is difficult. The fragileness of the hair like bars make the cross hair sight very susceptible to failure. Having edges, the hairs cause additional light diffractions. This additional diffraction occurs at the center of the cross hair peep. A critical area of any peep. The additional diffraction causes the cross hair peep to perform very poorly in low light.
An adjustable peep allows the user to increase the size of the peep""s aperture when light is dim and decrease the size of the peep""s aperture when light is bright. No attempt is made to eliminate light diffraction from the aperture. The adjustable peep has all the shortcomings of a traditional peep and is more difficult to manufacture.
Currently, light diffraction is being ignored by designers of peeps. The inadequacies caused by light diffraction, such as false aperture, oversized aperture, and poor performance under low light conditions are being ignored. There is a need for a peep sight that eliminates diffracted light from the peep sight""s aperture. A peep sight designed to eliminate diffracted light from its aperture would be simple, and traditionally expectable, also more accurate and useful under all light conditions.
Besides the objects and advantages described in the prior art, several objects and advantages of the current invention are:
A. to provide an aperture that is consistent in size and shape;
B. to provide a small aperture; and
C. to provide an aperture that performs well under all light conditions.
Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.